A light-emitting diode (LED), which is a type of semiconductor light-emitting element, is smaller and exhibits higher efficiency than other light sources that utilize discharge or radiation. In addition, recent improvements in luminous flux of LEDs have been expanding the range of application thereof, from conventional displaying use to lighting use.
In particular, bulb-type LED lamps that are attachable to sockets for conventional incandescent light bulbs and the likes have been introduced as alternatives to the conventional light bulbs.
Meanwhile, the related supply voltage of a conventional light bulb is generally 100 [V], 24 [V] or 12 [V], whereas the drive voltage of a Single LED is in the range of 3 [V] to 4 [V]. Thus, generally, a required number of LED chips are serially connected on a printed wiring board to suit the supply voltage (see Patent Literature 1).
For the use of an LED lamp as an alternative to a light bulb, it is necessary to arrange a required number of LEDs in a limited area. However, there is a limit to how much the intervals between the LED chips on the printed wiring board can be reduced.
In view of this, a semiconductor light-emitting device including a plurality of LED elements serially connected within each single chip by thin-film wiring has been developed (See Patent Literature 2). According to this technology, the LED elements, manufactured at the same time in the semiconductor manufacturing process, are electrically connected by thin-film wiring in the same semiconductor manufacturing process.
The following shows an overview of the semiconductor light-emitting device disclosed in Patent Literature 2. First, a semiconductor multilayer film, which includes a first conductive layer of n-type, a light-emitting layer and a second conductive layer of p-type formed over a SiC substrate in the stated order, is partitioned by etching into a plurality of light-emitting elements in a matrix, each having a square shape in plan view. A small square portion in plan view is removed by etching from one of the four corners of each light-emitting element so that a square portion of the first conductive layer is exposed. An n-electrode is formed on the exposed square portion of the first conductive layer. Also, a p-electrode is formed on the second conductive layer which remains in a hook-like shape. Then, an insulating film is formed between the p-electrode of a light-emitting element and the n-electrode of another light-emitting element adjacent thereto, and the p-electrode and the n-electrode are electrically connected with each other via thin-film wiring running on the insulating film. After that, the SiC substrate is divided by dicing into a plurality of separate chips, each having a plurality of light-emitting elements. Thus, semiconductor light-emitting device chips, each having a plurality of light-emitting elements, are manufactured.
In such a semiconductor light-emitting device, the distance between adjacent light-emitting elements is equal to the minimum width of the portion of the semiconductor multilayer film that is removable by etching in the semiconductor manufacturing process. Thus, the light-emitting elements can be integrated in high density.